Szohr will play Gretchen, a whip-smart ER nurse with a dark past. Riesgraf will take on the role of the wife of O'Mara's character, John Ellis. Samantha Ellis is described as an attractive, intelligent lawyer trying her best to keep her life together after losing her daughter to cancer.

Stamile has been cast as Bridget, an excellent doctor who suffers from a serious lack of empathy for her patients and colleagues, particularly John, whom she takes to task for coddling his patients. Grosse fills the shoes of a dedicated physician named Dan who is the closest thing John has to a friend.

In Complications, O'Mara stars as John, a disillusioned suburban ER doctor whose life is changed after he intervenes in a drive-by shooting, saving a young boy's life while killing one of his attackers.